In a unity power vision-assisting device, such as a monocular, the device is collimated when the output optical axis matches the input optical axis such that the beam of light entering the device is parallel with the beam of light exiting the device. During manufacturing of the device, a technician typically aligns the optical axes through an iterative process that requires adjustment of the device, securement of the components of the device relative to one another, and determination of whether the device is satisfactorily collimated. If the device is not satisfactorily collimated, the technician must release some of the previously secured components of the device relative to one another and readjust the device. This process may not necessarily collimate the device to the desired degree of collimation. A need exists, therefore, to provide a monocular that includes a mechanism for collimating the output optical axis with the input optical axis to a desired degree of collimation.